Process for producing photographic dye images



"Patented Nov. 2, 1943 PROCESS FOR PRODUCING PHOTOGRAPHIC DYE Ill/[AGES Laszl Schwarc, Brussels-Uccle, Belgium, assignby mesne assignments, to-Chromogen, In-

corporated, a corporation of Nevada No Drawing. Application December 4, 1939, Se-

rial No. 307,506. 19, 1938 7 Claims.

According to a known method of producing .colored photographic images, color formers, e. g.

diazo compounds are incorporated in a lightsensitive silver halide layer and the exposed and developed layer is subjected to two treatments,

, the first of which consists in the conversion of the diazo compounds diffusely throughout the layer into the corresponding azo dye and the second of which consists in a selective destruction of the dye at the image or non-image parts of the layer. An alternative of this process involves a selective destruction of the color former at the image or non-image parts of the exposed and developed layer and conversion of the remaining color former into the dye.

The present invention consists in a new and simplified method of obtaining a positive dyeimage direct from a negative silver image or a negative dye-image from a positive silver image. It has been found that the formation of an azo dye in a photographic layer from a diazo compound and a coupling compound may be caused to take place locally by the addition of heavy metal compounds, such as chromium copperor iron-salts. Suitable compounds are, for example,-

copper sulphate, copper chloride, ferric chloride, ferrous chloride, potassium ferrocyanide, potassium ferricyanide or potassium bichromate.

In Great Britain December One method of practicing the process of the I present invention consists in treating a photographic layer containing a silver image and an amine in a diazotizing solution in presence of a heavy metal salt and thereafter treating the layer containing the diazo compound thus obtained in a solution containing a coupling component.

Example 1.- A light-sensitive silver halide emulsion layer is treated'in a 0.75% solution of Primuline sulphonic acid for 25 minutes and dried. The layer is exposed, developed and fixed in the usual manner. Instead of impregnating the layer withthe Primuline sulphonic acid before the exposure, the impregnation may also be eifected with the exposed layer containing the silver image. The layer is thereupon treated for three minutes at a temperature of C. in a diazotizing solution containing:

2n hydrochloric acid ccs 2n sodium nitrite sclution ccs 0.4 10% copper sulphate solution ccs 0.2 Water ccs '74 After this treatment, the layer is washed for a short time and the diazo compound formed therein is coupled by treating the layer in a 1% solution of N-(p-toluenesulphonyl) -H-acid in a 0.1n solution of sodium carbonate. The silver still present in the dye image thus obtained is then blea hed out to form a soluble silver salt and removed by hypo. The magenta dye is obtained at the parts where no silver was present.

Example 2.Thediazotizing bath used in Example 1 may be replaced by the llowing solution employed for one minute at 8 C.:

2n hydrochloric acid ccs 20 2n sodium nitrite solution ccs 0.3 4% potassium ferricyanide solution ccs 1 Water '78 Instead of adding the metal salt to the diazotizing solution, the formation of the diazo compound may be carried out with the usual bath and the film thereafter treated in a solution of the metal salt, as illustrated in the following example. I

Example 3.A film containing a silver image and impregnated with Primuline sulphonic acid is treated for one minute at 18 C. in a solution containing:

n Sulphuric acid ccs 200 2n sodium nitrite solution ccs 0.5

After this diazotization the film is treated for one minute at 19 C. in the following bath:

2n hydrochloric acid ccs 10 10% copper sulphate solution ccs 0.5 Water ccs After this treatment the layer is washed for a short time and the diazo compound formed-therein is coupled by treatingthe layer in a 1% s0lution of toluol-sulphonated H-acid in a 0.1n solution of sodium carbonate. The silver still present in the dye-image thus obtained is then bleached out to form a soluble silver salt and removed by hypo.

A magenta dye is obtained at the places where no silver was present, as in Examples 1 and 2.

The duration of the treatment in the metal-salt solution depends on the concentration of the metalsalt. If, for example, more highly diluted copper sulphate solutions are employed than described in Examp e 3 the treatment must be prolonged. The separate application of the nitrite solution and the metal salt, solution has the advantage that the nitrite solution is not decomposed so readily as otherwise.

I In a similar manner the heavy metal salt may instead be added to the solution containing the :oupling component, as instanced in the following example.

Example 4.A film containing a silver image and impregnated with Primuline sulphonic acid is treated for one minute at 18 C. in a solution containing: I

0.5n sulphuric acid ccs 200 2n sodium nitrite solution ccs 0,5

, isimpregnated with a 0.5%

sulphonated H-acid in a 0.5%

may advantageouslybe employed for vention is to incorporate a. coupling component in thelayer and, after exposure and development of the silver image, to couple the coupling'component in the solution of a diazo compound conta ing a heavy metal salt. Inthis case also the d e-is obtained at the non-image parts.

/ Example 5.-A film containing a silver image solution of toluoL- solution of sodium forming the ldye-images therein as above described.

The aminesused in carrying, out the present should be of such kind as are not easily invention washed out of the layer and do not diffuse into adjacent layers.

What is claimed is: 1. A processfor producing a reversed dyeimage from a sliver image within a developed photographic layer which-involves the synthesis of an azo dyewithin said layer containing said silver image from reactive components compriscarbonate. The layer is thereupon washed for a short time and dried. Then it is treated for one minute at 18 C. in a solution containing:

1% diazo-sulphanilic acid ccs 20 10% copper sulphate solution ccs 2 20% sodium chloride solution. .ccs 2 Amagenta dye is thus obtained at the places where no silver was present.

The formation of a dye may also belocalized by converting the silver at the image places'into a copper salt, e. g. cuprous halide or copper ferrocyanide, prior to effecting the diazotizing according to the following example.

Example 6.A film containing a silver image and impregnated with an amine is treated in a solution of potassium ferricyanide and a copper 'salt, whereby a copper ferrocyanide image is formed in place of the silver. If thereafter the amine is diazotized and'coupled with a coupling component, the azo dye is formed only at the places where no silver was present. The copper ferrocyanide formed as above described. is deing a diazo compound and an azo coupler, one of said reactive components being diffusely distributed throughout said layer and the other reactive component being applied to said layer in a treating solution comprising the step of treating said layer containing the reactive component difiusely distributed therethrough with a heavy metal compound in solution at a point in said.

' process not after said other reactive component composed by the sodium carbonate contained in the coupler solution and may therefore be fixed out immediately.

Example 7.-'-A film containing a silver image and impregnated with Primuline sulphonic acid as described in Example 1 is treated in a bath containing: 10% copper sulphate solution' ccs 20 4% potassium bromide solution ccs 10 Thereafter the filmis diazotized for one minute at 18 C. with a solution containing:

' 0.5n sulphuric acid ccs 1'00 2n sodium nitrite solution .';ccs 0.4

and thereafter immersed in a 1% solution of toluol-sulphonated H-acid in a 0.1n solution .of

-soduim carbonate. 'Again the dye is obtained at the places where no silver was present.

Instead of thePrimuline sulphonic acid used 'in the examples above described various other amines or azo-coupling components may be used. Suitable compounds are, for example, Diazolicthh gelb G (Ullmann Enzyklopiidie der technisc en Chemie, 2nd ed. 1929, vol. 3, page 659), Diazolichtgelb 2 G (Schultz Farbstoiftabellen,'Leipzig 1931, 7th ed., vol. 1, No. 749), Diazollichtgelb 3 GL (Schultz Farbstofltabellen, Leipzig 1932, 7th ed., vol. 2, page 80) and Diazoechtgelb 3 GLL or 3 RL. (both Schultz 1.0., vol. 2, age '11) the present invention the treatment' of. a multilayer material-by incorporating different amines in the silver halide emulsion lay- 'ers sensitized. to differently colored light and flhe process described in is applied to said layer and applying said other reactive component to said layer at a point in said process not previous to the treatment with said compound, said compound being capable of preventing permanent formation of the dye at the pointsof the silver image without afiecting the coupling properties of said reactive components at points other than the points of the silver image whereby a dye image is formed in inverse proportion to, the quantity'of silver deposit in said silver image.

2. A' process for producing a reversed dyeimage-from a silver image within a developed photographic layer which involves the synthesis of an azo dye within said layer containing said .silver image from reactive components comprising a diazo compound and an azo coupler, one of said reactive components being diiiusely distributed throughout said layer, which comprises the step of treating said layer already containing said one reactive component with the other reactive component in solution anc'l in the presence of a heavy metal compound diffusely distributed with respect to said layer, said compound being capable of preventing permanent formation of the dye at the points of the silver image without affecting the coupling properties of said reactive coinponents at points other than the points of the silver image whereby a dye image is formed in inverseproportion to the quantity of silver deposit insaid silver image.

3. A process for producing a reversed dyeimage from a silverimage within a developed photographic layer which involves the synthesis I of an azo dye within said layer containing said silver image from reactive components comprising a diazo compound and an azo coupler, one of said-reactive components being diffusely distributed throughout said layer, which comprises consisting of chromium, copper and iron and the step of treating said layer already containing said one reactive component withthe other reacv tive component in solution and in the presence of a heavy metal compound difiusely distributed with respect 'to said layer, said compound being selected from compounds of the metal group being capable of preventing permanent formation of the dye at the points of the silver image without affecting the coupling properties of said reactive components at points other than the points of the=silver image whereby a dye image is formed in inverse profir tion to the quantity of silver deposit in said silverimage.

4. A process for producing a reversed dyeimage from a silver image within a developed photographic layer which involves the synthesis of an azo dye within said layer containing said silver image from reactive components comprising a diazo compound and an azo coupler, said diazo compound being diffusely distributed throughout said layer, which comprises the step of treating said layer alreadylcontaining said diazo compound with an azo coupler in solution and in the presence of a heavy metal compound diffusely distributed with respect to said layer, said compound being capable of preventing permanent formation of the dye at the points of the silver image without affecting the coupling properties'of said diazo compound and said azo coupler at points other than the points of the silver image whereby a dye is formed in inverse proportion to the quantity of silver deposit in said silver image.

5. A process for producing a reversed dyeimage from a silver image within a developed photographic layer which involves the synthesis of an azo dye within said layer containing said silver image, comprising the step of forming a diazo compound diffusely distributed throughout said layer and coupling said diazo compound with an azo coupler applied to said layer already containing said diazo compound in the presence of a heavy metal compound difi'usely distributed with respect to said layer, said azo coupler being applied to said layer already containing said diazo compound at a, point in said process not previous to the introduction of said heavy metal compound and said heavy metal compound being capable of preventing permanent formation of the dye at the points of the silver image without afl'ecting the coupling properties of said diazo compound and said azo coupler at points other than the points of the silver image whereby a dye is formed in inverse proportion to the quantity of 'silver deposit in said silver image.

6. A process for producing a reversed dyeimage from a silver imagewithin a developed photographic layer which involves the synthesis of an azo dye within said layer containing said silver image, comprising the steps of treating such a layer already containing an azo coupler difiusely distributed therethrough with a heavy metal compound in solution and a diazo compound, said diazo compound being applied to said layer already containing said azo coupler at a point in said process not previous to the application of said heavy metal compound thereby to couple said diazo compound and said azo coupler in the presence of said heavy metal compound, said compound being capable of preventing permanent formation of the dye at the points of the silver image without affecting the coupling properties of said azo coupler and said diazo compound at points other than the points of the silver image whereby a dye image is formed in inverse proportion to the quantity of silverdeposit in said silver image.

7. A process for producing a reversed dyeimage from a silver image within a developed photographic layer which involves the synthesis of an azo dye within said layer containing said silver image, comprising the step of forming a diazo compound difiusely distributed throughout said layer and coupling said diazo compound with an azo coupler applied to said layer already containing said diazo compound in the presence of a heavy metal compound, said azo coupler being applied to said layer already containing said diazo compound at a point in said process not previous to the introduction of said-heavy metal compound and said heavy metal compound being capable of preventing permanent formation of the dye at the points of the silver image without affecting the coupling properties of said diazo compound and said azo coupler at points other. than the points of the silver image, whereby a dye is formed in inverse proportion to the quantity of silver deposit in said silver image.

LAszLo SCHWARC. 

